The invention relates to diaphragm spring friction clutches.
A typical diaphragm spring clutch comprises a cover member, a pressure plate mounted with respect to the cover member and a diaphragm spring interposed between the cover member and the pressure plate. In use the clutch is mounted on a flywheel and a driven plate is interposed between the flywheel and pressure plate. The diaphragm spring urges the pressure plate into frictional engagement with the driven plate and the driven plate into frictional engagement with the flywheel. A diaphragm spring typically incorporates an outer annular plate spring or belville portion and fingers projecting inwardly from the belville portion. The inner ends of the fingers are deflected in order to deform the belville portion and thus release the clutch. Flexibility in the fingers and particularly near the outer ends of the fingers results in an undesirable increase in the travel required in the clutch release mechanism to release the clutch. There have been various proposals to increase the stiffness of the fingers, for example by bending them to a shallow `V` or channel section to in effect provide them with longitudinal ribs.
An objective of the present invention is to provide an improved diaphragm spring friction clutch with effective stiffening of the diaphragm spring fingers.